古菌 T4F 机器的多样化与功能扩展
Diversification and functional expansion of archaeal T4F machineries
研究用新构建的 MacSyFinder2 模型对古菌 T4F 系统进行鉴定与分类，发现其多样性远超预期，许多生物携带一套或多套组装机器。基于结构系统发育分析显示，T4F 相关 ATPase 可变的 N 端结构域与子系统聚类一致，提示核心机器通过结构创新在古菌分泌 ATPase 家族内发生分化。
来源：PLOS Genetics · journals.plos.org
by Shamphavi Sivabalasarma, Sonja-Verena Albers
Archaea have several cell surface structures belonging to the type 4 filament (T4F) superfamily. All share a minimal core assembly system consisting of an ATPase, a platform protein, a filament-forming protein, and a class III signal peptidase. Here, we generated novel MacSyFinder2 models to identify and classify archaeal T4F systems. Our analysis revealed a vast diversity of archaeal T4F, with many organisms harboring one or more assembly machineries. Structure-based phylogenetic analysis showed that the variable N-terminal domain of T4F-related ATPases mirrors the subsystem clustering, indicating that the core machinery has diversified within the archaeal secretion ATPase family through structural innovation. Genome-wide screening for signal peptidase III cleavage site (SPIII) containing proteins revealed the widespread presence of substrate-binding proteins carrying a class III signal peptide. We propose that these binding proteins, with canonical SPIII cleavage sites, functionalize T4F machineries for efficient substrate scavenging, expanding the functional repertoire of archaeal T4F systems beyond their currently characterized roles.